图片右上角加小红圈c#代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace huaquanshengqi
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                string number = textBox2.Text;
                string imageurl = textBox1.Text;
                Image img = Image.FromFile(imageurl);
                Brush brush = Brushes.Coral;
                int ImageWidth, ImageHeight;
                pictureBox1.Image = img;
                ImageWidth = img.Width;
                ImageHeight = img.Height;
                Graphics g = Graphics.FromImage(img);
                SolidBrush brush1 = new SolidBrush(Color.Wheat);//数字样式
                SolidBrush brush2 = new SolidBrush(Color.Red);//圆圈样式
                //Graphics g = this.pictureBox1.CreateGraphics();
                //Pen p = new Pen(Color.Red);
                Font font = new Font("Arial",30);
                g.FillEllipse(brush2, ImageWidth - 50, 0, 50, 50);
                if (number==String.Empty)
                {
                    g.DrawString("1",font,brush1,ImageWidth-45,3);
                }
                else
                {
                    string RegStr = @"^\d$";
                    System.Text.RegularExpressions.Regex rg = new System.Text.RegularExpressions.Regex(RegStr);
                    if (rg.IsMatch(number))//判断是不是一位数字
                    {
                        g.DrawString(number, font, brush1, ImageWidth - 45, 3);
                    }
                    else
                    {
                        textBox2.Text = "请输入一位数字";
                    }
            }
        }
        catch (Exception)
        {
            textBox1.Text = "请输入正确的路径";
        }
    }
    private void button2_Click(object sender, EventArgs e)
    {
        SaveFileDialog save=new SaveFileDialog();
        save.Filter = "(*.jpg)|*.jpg";
        save.FilterIndex = 2;
        save.RestoreDirectory = true;
        if (save.ShowDialog()==DialogResult.OK)
        {
            this.pictureBox1.Image.Save(save.FileName,System.Drawing.Imaging.ImageFormat.Jpeg);
        }
    }
    private void textBox1_TextChanged(object sender, EventArgs e)
    {
    }
    }
}